所以我想以编程方式在我的View中将UILabel水平和垂直居中。我按照this topic但不起作用。我怎么能这样做？
p / s：这是我的代码：
Imports System.Data.OleDb
Public Class dbImports
Public Shared Function importDatabase(con As OleDbConnection, importsCon As OleDbConnection)
Dim tr As OleDbTransaction = Nothing
Dim sql As New OleDbCommand
sql.Connection = con
sql.CommandType = CommandType.Text
Try
tr = con.BeginTransaction()
sql.CommandText = "DELETE FROM tblModules"
sql.Transaction = tr
sql.CommandText = "DELETE FROM tblContracts"
sql.Transaction = tr
sql.CommandText = "DELETE FROM tblContractText"
sql.Transaction = tr
sql.CommandText = "DELETE FROM tblEmailSettings"
sql.Transaction = tr
sql.CommandText = "DELETE FROM tblIncidents"
sql.Transaction = tr
sql.CommandText = "DELETE FROM tblInvoiceLog"
sql.Transaction = tr
sql.CommandText = "DELETE FROM tblMailLog"
sql.Transaction = tr
sql.CommandText = "DELETE FROM tblModuleNames"
sql.Transaction = tr
sql.CommandText = "DELETE FROM tblRecurring"
sql.Transaction = tr
sql.CommandText = "DELETE FROM tblSystemSettings"
sql.Transaction = tr
sql.CommandText = "SELECT * FROM tblContracts ORDER BY ContractID"
sql.Transaction = tr
Dim sqlct As String
sqlct = sql.CommandText
For Each dr As DataRow In getDataTable(sqlct, importsCon, Nothing).Rows
Dim conID As Integer
Dim custacc As String
Dim datestart As Object
Dim daterenew As Object
Dim fee As Double
Dim agree As String
Dim details As String
Dim datesent As Object
Dim timesent As Object
Dim remname As String
Dim remmail As String
conID = dr("ContractID")
custacc = dbToString(dr("CustAcc"))
datestart = dbToDate(dr("DateStart"))
daterenew = dbToDate(dr("DateRenew"))
fee = dr("Fee")
agree = dbToString(dr("Agreement"))
details = dbToString(dr("OtherDetails"))
datesent = dbToDate(dr("DateSent"))
timesent = dbToTime(dr("TimeSent"))
remname = dbToString(dr("ReminderName"))
remmail = dbToString(dr("ReminderEmail"))
sql.CommandText = "INSERT INTO tblContracts(ContractID, CustAcc, DateStart, DateRenew, Fee, Agreement, OtherDetails, DateSent, TimeSent, ReminderName, ReminderEmail) VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)"
sql.Transaction = tr
sql.Parameters.Add("@ContractID", OleDbType.Integer).Value = conID
sql.Parameters.Add("@CustAcc", OleDbType.VarChar).Value = custacc
sql.Parameters.Add("@DateStart", OleDbType.DBDate).Value = datestart
sql.Parameters.Add("@DateRenew", OleDbType.DBDate).Value = daterenew
sql.Parameters.Add("@Fee", OleDbType.Double).Value = fee
sql.Parameters.Add("@Agreement", OleDbType.VarChar).Value = agree
sql.Parameters.Add("@OtherDetails", OleDbType.VarChar).Value = details
sql.Parameters.Add("DateSent", OleDbType.DBDate).Value = datesent
sql.Parameters.Add("@TimeSent", OleDbType.DBTime).Value = timesent
sql.Parameters.Add("@ReminderName", OleDbType.VarChar).Value = remname
sql.Parameters.Add("@remmail", OleDbType.VarChar).Value = remmail
Next
sql.CommandText = "SELECT * FROM tblContractText ORDER BY pk"
sql.Transaction = tr
sqlct = sql.CommandText
For Each dr As DataRow In getDataTable(sqlct, importsCon, Nothing).Rows
Dim Para1 As String
Dim pk As Integer
Dim BillPara As String
Para1 = dbToString(dr("Para1"))
pk = dr("pk")
BillPara = dbToString(dr("BillPara"))
sql.CommandText = "INSERT INTO tblContractText(Para1, pk, BillPara) VALUES(?, ?, ?)"
sql.Transaction = tr
sql.Parameters.Add("@Para1", OleDbType.LongVarChar).Value = Para1
sql.Parameters.Add("@pk", OleDbType.Integer).Value = pk
sql.Parameters.Add("@BillPara", OleDbType.LongVarChar).Value = BillPara
Next
sql.CommandText = "SELECT * FROM tblEmailSettings ORDER BY ID"
sql.Transaction = tr
sqlct = sql.CommandText
For Each dr As DataRow In getDataTable(sqlct, importsCon, Nothing).Rows
Dim ID As String
Dim PW As String
Dim Subject As String
Dim Body As String
Dim SMTP As String
Dim conf As Boolean
Dim invSub As String
Dim invBody As String
ID = dbToString(dr("ID"))
PW = dbToString(dr("PW"))
Subject = dbToString(dr("Subject"))
Body = dbToString(dr("Body"))
SMTP = dbToString(dr("SMTPHost"))
conf = dbToBoolean(dr("Confirmation"))
invSub = dbToString(dr("invSubject"))
invBody = dbToString(dr("invBody"))
sql.CommandText = "INSERT INTO tblEmailSettings(ID, PW, Subject, Body, SMTPHost, Confirmation, invSubject, invBody) VALUES(?, ?, ?, ?, ?, ?, ?, ?)"
sql.Transaction = tr
sql.Parameters.Add("@ID", OleDbType.VarChar).Value = ID
sql.Parameters.Add("@PW", OleDbType.VarChar).Value = PW
sql.Parameters.Add("@Subject", OleDbType.VarChar).Value = Subject
sql.Parameters.Add("@Body", OleDbType.LongVarChar).Value = Body
sql.Parameters.Add("@SMTPHost", OleDbType.VarChar).Value = SMTP
sql.Parameters.Add("@Confimation", OleDbType.Boolean).Value = conf
sql.Parameters.Add("@invSubject", OleDbType.LongVarChar).Value = invSub
sql.Parameters.Add("@invBody", OleDbType.LongVarChar).Value = invBody
Next
sql.CommandText = "SELECT * FROM tblIncidents ORDER BY supportID"
sql.Transaction = tr
sqlct = sql.CommandText
For Each dr As DataRow In getDataTable(sqlct, importsCon, Nothing).Rows
Dim supportID As Integer
Dim clientName As String
Dim dateStart As Object
Dim dateEnd As Object
Dim incidentProblem As String
Dim timeStart As Object
Dim timeEnd As Object
Dim incidentSolved As Boolean
Dim incidentSolution As String
supportID = (dr("supportID"))
clientName = dbToString(dr("clientName"))
dateStart = dbToDate(dr("dateStart"))
dateEnd = dbToDate(dr("dateEnd"))
incidentProblem = dbToString(dr("incidentProblem"))
timeStart = dbToTime(dr("timeStart"))
timeEnd = dbToTime(dr("timeEnd"))
incidentSolved = dbToBoolean(dr("incidentSolved"))
incidentSolution = dbToString(dr("incidentSolution"))
sql.CommandText = "INSERT INTO tblIncidents(supportID, clientName, dateStart, dateEnd, incidentProblem, timeStart, timeEnd, incidentSolved, incidentSolution) VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?)"
sql.Transaction = tr
sql.Parameters.Add("@supportID", OleDbType.Integer).Value = supportID
sql.Parameters.Add("@clientName", OleDbType.VarChar).Value = clientName
sql.Parameters.Add("@dateStart", OleDbType.DBDate).Value = dateStart
sql.Parameters.Add("@dateEnd", OleDbType.DBDate).Value = dateEnd
sql.Parameters.Add("@incidentProblem", OleDbType.LongVarChar).Value = incidentProblem
sql.Parameters.Add("@timeStart", OleDbType.DBTime).Value = timeStart
sql.Parameters.Add("@timeEnd", OleDbType.DBTime).Value = timeEnd
sql.Parameters.Add("@incidentSolved", OleDbType.Boolean).Value = incidentSolved
sql.Parameters.Add("@incidentSolution", OleDbType.LongVarChar).Value = incidentSolution
Next
sql.CommandText = "SELECT * FROM tblInvoiceLog ORDER BY BatchNumber"
sql.Transaction = tr
sqlct = sql.CommandText
For Each dr As DataRow In getDataTable(sqlct, importsCon, Nothing).Rows
Dim BatchNumber As Integer
Dim BatchLine As Integer
Dim DatePosted As Object
Dim AccCode As String
Dim Description As String
Dim Period As String
Dim TotalFee As Double
BatchNumber = dr("BatchNumber")
BatchLine = dr("BatchLine")
DatePosted = dbToDate(dr("DatePosted"))
AccCode = dbToString(dr("AccCode"))
Description = dbToString(dr("Description"))
Period = dbToString(dr("Period"))
TotalFee = dr("TotalFee")
sql.CommandText = "INSERT INTO tblInvoiceLog(BatchNumber, BatchLine, DatePosted, AccCode, Description, Period, TotalFee) VALUES(?, ?, ?, ?, ?, ?, ?)"
sql.Transaction = tr
sql.Parameters.Add("@BatchNumber", OleDbType.Integer).Value = BatchNumber
sql.Parameters.Add("@BatchLine", OleDbType.Integer).Value = BatchLine
sql.Parameters.Add("@DatePosted", OleDbType.DBDate).Value = DatePosted
sql.Parameters.Add("@AccCode", OleDbType.VarChar).Value = AccCode
sql.Parameters.Add("@Description", OleDbType.LongVarChar).Value = Description
sql.Parameters.Add("@Period", OleDbType.VarChar).Value = Period
sql.Parameters.Add("@TotalFee", OleDbType.Double).Value = TotalFee
Next
sql.CommandText = "SELECT * FROM tblMailLog ORDER BY mailID"
sql.Transaction = tr
sqlct = sql.CommandText
For Each dr As DataRow In getDataTable(sqlct, importsCon, Nothing).Rows
Dim mailID As Integer
Dim Sender As String
Dim Receiver As String
Dim FileName As String
Dim DateSent As Object
Dim TimeSent As String
Dim Body As String
Dim AccCode As String
mailID = dr("mailID")
Sender = dbToString(dr("Sender"))
Receiver = dbToString(dr("Receiver"))
FileName = dbToString(dr("FileName"))
DateSent = dbToDate(dr("DateSent"))
TimeSent = dbToString(dr("TimeSent"))
Body = dbToString(dr("Body"))
AccCode = dbToString(dr("AccCode"))
sql.CommandText = "INSERT INTO tblMailLog(mailID, Sender, Receiver, FileName, DateSent, TimeSent, Body, AccCode) VALUES(?, ?, ?, ?, ?, ?, ?, ?)"
sql.Transaction = tr
sql.Parameters.Add("@mailID", OleDbType.Integer).Value = mailID
sql.Parameters.Add("Sender", OleDbType.VarChar).Value = Sender
sql.Parameters.Add("Receiver", OleDbType.VarChar).Value = Receiver
sql.Parameters.Add("@FileName", OleDbType.VarChar).Value = FileName
sql.Parameters.Add("@DateSent", OleDbType.DBDate).Value = DateSent
sql.Parameters.Add("@TimeSent", OleDbType.VarChar).Value = TimeSent
sql.Parameters.Add("@Body", OleDbType.LongVarChar).Value = Body
sql.Parameters.Add("@AccCode", OleDbType.VarChar).Value = AccCode
Next
sql.CommandText = "SELECT * FROM tblModuleNames"
sql.Transaction = tr
sqlct = sql.CommandText
For Each dr As DataRow In getDataTable(sqlct, importsCon, Nothing).Rows
Dim fModule As String
fModule = dbToString(dr("Module"))
sql.CommandText = "INSERT INTO tblModuleNames(Module) VALUES(?)"
sql.Transaction = tr
sql.Parameters.Add("@Module", OleDbType.VarChar).Value = fModule
Next
sql.CommandText = "SELECT * FROM tblModules ORDER BY ModuleID"
sql.Transaction = tr
sqlct = sql.CommandText
For Each dr As DataRow In getDataTable(sqlct, importsCon, Nothing).Rows
Dim ModuleID As Integer
Dim ModuleName As String
Dim NumberUsers As String
Dim License As String
Dim Username As String
Dim ContractID As Integer
ModuleID = dr("ModuleID")
ModuleName = dbToString(dr("ModuleName"))
NumberUsers = dbToString(dr("NumberUsers"))
License = dbToString(dr("License"))
Username = dbToString(dr("Username"))
ContractID = dr("ContractID")
sql.CommandText = "INSERT INTO tblModules(ModuleID, ModuleName, NumberUsers, License, Username, ContractID) VALUES(?, ?, ?, ?, ?, ?)"
sql.Transaction = tr
sql.Parameters.Add("@ModuleID", OleDbType.Integer).Value = ModuleID
sql.Parameters.Add("@ModuleName", OleDbType.VarChar).Value = ModuleName
sql.Parameters.Add("@NumberUsers", OleDbType.VarChar).Value = NumberUsers
sql.Parameters.Add("@License", OleDbType.VarChar).Value = License
sql.Parameters.Add("@Username", OleDbType.VarChar).Value = Username
sql.Parameters.Add("ContractID", OleDbType.Integer).Value = ContractID
Next
sql.CommandText = "SELECT * FROM tblRecurring ORDER BY billID"
sql.Transaction = tr
sqlct = sql.CommandText
For Each dr As DataRow In getDataTable(sqlct, importsCon, Nothing).Rows
Dim billID As Integer
Dim DateStart As Object
Dim DateNext As Object
Dim Fee As Double
Dim Description As String
Dim AccountCode As String
Dim Notes As String
billID = dr("billID")
DateStart = dbToDate(dr("DateStart"))
DateNext = dbToDate(dr("DateNext"))
Fee = dr("Fee")
Description = dbToString(dr("Description"))
AccountCode = dbToString(dr("AccountCode"))
Notes = dbToString(dr("Notes"))
sql.CommandText = "INSERT INTO tblRecurring(billID, DateStart, DateNext, Fee, Description, AccountCode, Notes) VALUES(?, ?, ?, ?, ?, ?, ?)"
sql.Transaction = tr
sql.Parameters.Add("@billID", OleDbType.Integer).Value = billID
sql.Parameters.Add("@DateStart", OleDbType.DBDate).Value = DateStart
sql.Parameters.Add("@DateNext", OleDbType.DBDate).Value = DateNext
sql.Parameters.Add("@Fee", OleDbType.Double).Value = Fee
sql.Parameters.Add("@Description", OleDbType.LongVarChar).Value = Description
sql.Parameters.Add("@AccountCode", OleDbType.VarChar).Value = AccountCode
sql.Parameters.Add("@Notes", OleDbType.LongVarChar).Value = Notes
Next
sql.CommandText = "SELECT * FROM tblSystemSettings ORDER BY ID"
sql.Transaction = tr
sqlct = sql.CommandText
For Each dr As DataRow In getDataTable(sqlct, importsCon, Nothing).Rows
Dim ID As Integer
Dim listContractsX As Integer
Dim listContractsY As Integer
Dim invoiceLogX As Integer
Dim invoiceLogY As Integer
Dim mailLogX As Integer
Dim mailLogY As Integer
Dim recurringX As Integer
Dim recurringY As Integer
Dim reportsX As Integer
Dim reportsY As Integer
ID = dr("ID")
listContractsX = dr("listContractsX")
listContractsY = dr("listContractsY")
invoiceLogX = dr("invoiceLogX")
invoiceLogY = dr("invoiceLogY")
mailLogX = dr("mailLogX")
mailLogY = dr("mailLogY")
recurringX = dr("recurringX")
recurringY = dr("recurringY")
reportsX = dr("reportsX")
reportsY = dr("reportsY")
sql.CommandText = "INSERT INTO tblSystemSettings(ID, listContractsX, listContractsY, invoiceLogX, invoiceLogY, mailLogX, mailLogY, recurringX, recurringY, reportsX, reportsY) VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)"
sql.Transaction = tr
sql.Parameters.Add("@ID", OleDbType.Integer).Value = ID
sql.Parameters.Add("@listContractsX", OleDbType.Integer).Value = listContractsX
sql.Parameters.Add("@listContractsY", OleDbType.Integer).Value = listContractsY
sql.Parameters.Add("@invoiceLogX", OleDbType.Integer).Value = invoiceLogX
sql.Parameters.Add("@invoiceLogY", OleDbType.Integer).Value = invoiceLogY
sql.Parameters.Add("@mailLogX", OleDbType.Integer).Value = mailLogX
sql.Parameters.Add("@mailLogY", OleDbType.Integer).Value = mailLogY
sql.Parameters.Add("@recurringX", OleDbType.Integer).Value = recurringX
sql.Parameters.Add("@recurringY", OleDbType.Integer).Value = recurringY
sql.Parameters.Add("@reportsX", OleDbType.Integer).Value = reportsX
sql.Parameters.Add("@reportsY", OleDbType.Integer).Value = reportsY
Next
tr.Commit()
MsgBox("Import Completed!")
Catch ex As Exception
tr.Rollback()
Throw
End Try
End Function
Public Shared Function getDataTable(ByVal sqlct As String, importsCon As OleDbConnection, tr As OleDbTransaction) As DataTable
Dim sql As OleDbCommand
Dim da As OleDbDataAdapter
Dim dt As New DataTable
If tr IsNot Nothing Then
sql = New OleDbCommand(sqlct, importsCon, tr)
Else
sql = New OleDbCommand(sqlct, importsCon)
End If
da = New OleDbDataAdapter(sql)
da.Fill(dt)
Return dt
End Function
答案 0 :(得分：4)
将此添加到您的代码中：
noDataLabel.translatesAutoresizingMaskIntoConstraints = false
来自苹果文档：
默认情况下，视图上的自动调整遮罩会产生 完全确定的约束 视图的位置。这允许自动布局系统跟踪其视图的帧 布局是手动控制的（例如通过-setFrame：）。 当您选择使用自动布局定位视图时，通过添加自己的约束， 您必须将此属性设置为NO。 IB会为你做这件事。
答案 1 :(得分：1)
您还需要为uilabel创建大小限制，如下所示，并将其添加到您的superView
NSLayoutConstraint(item: noDataLabel, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: 100)
NSLayoutConstraint(item: noDataLabel, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: 40)
您的实施将如下所示
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let noDataLabel = UILabel()
noDataLabel.text = "No data :("
noDataLabel.textColor = UIColor.redColor()
noDataLabel.font = UIFont.systemFontOfSize(20)
noDataLabel.sizeToFit()
noDataLabel.translatesAutoresizingMaskIntoConstraints = false
self.view.addSubview(noDataLabel)
let horizontal = NSLayoutConstraint(item: noDataLabel, attribute: .CenterX, relatedBy: .Equal, toItem: self.view, attribute: .CenterX, multiplier: 1.0, constant: 0.0).active = true
let vertical = NSLayoutConstraint(item: noDataLabel, attribute: .CenterY, relatedBy: .Equal, toItem: self.view, attribute: .CenterY, multiplier: 1.0, constant: 0.0).active = true
let width = NSLayoutConstraint(item: noDataLabel, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: 100)
let height = NSLayoutConstraint(item: noDataLabel, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: 40)
self.view.addConstraint(horizontal)
self.view.addConstraint(vertical)
self.view.addConstraint(width)
self.view.addConstraint(height)
}
}