Question

我使用swift使用xcode编写一个简单的应用程序。我创建了一个函数来计算BMR，但这里有一些问题。我该怎么办？这是我的代码：

import UIKit
class ViewController: UIViewController {     
    @IBOutlet var Age: UILabel!
    @IBOutlet var Height: UILabel!
    @IBOutlet var Weight: UILabel!
    @IBOutlet var agefield: UITextField!
    @IBOutlet var heightfield: UITextField!
    @IBOutlet var weightfield: UITextField!
    @IBOutlet var BMR: UILabel!
    @IBAction func Calculate(sender: UIButton) {
        var a = "66,0"
        var b = "13,7"
        var c = (weightfield.text as NSString).floatValue
        var d = "5,0"
        var e = (heightfield.text as NSString).floatValue
        var f = "6,8"
        var g = (agefield.text as NSString).floatValue
        var result = a + (b * c) + (d * e) - (f * g)
        BMR.text = "\(result)"

    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}

c，e和g值取决于文本字段 “var result”行有一个错误：“无法找到接受提供的参数的'+'的重载” 然后，我创建了一个游乐场，我用实数改变了c，e和g变量，它确实有效！

var a = 66.0
var b = 13.7
var c = 72.0
var d = 5.0
var e = 178.0
var f = 6.8
var g = 16.0

var result = a + (b * c) + (d * e) - (f * g)

print(result)

有什么想法吗？提前致谢

-

let a:Float = 66.0
let b:Float = 13.7
var c = (weightfield.text as NSString).floatValue
let d:Float = 5.0
var e = (heightfield.text as NSString).floatValue
let f:Float = 6.8
var g = (agefield.text as NSString).floatValue
var result = a + (b * c) + (d * e) - (f * g)
BMR.text = "\(result)"

六角，感谢您的宝贵帮助。这是更改的代码。没有问题：D ...但是有SIGABRT信号所以App无法运行。哪里出错？

-

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<Calculator.ViewController 0x7fcf28467e20> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key BMI.'
*** First throw call stack:
(
    0   CoreFoundation                      0x0000000109f77c65 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010bae2bb7 objc_exception_throw + 45
    2   CoreFoundation                      0x0000000109f778a9 -[NSException raise] + 9
    3   Foundation                          0x000000010a395b53 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 259
    4   CoreFoundation                      0x0000000109ebfd50 -[NSArray makeObjectsPerformSelector:] + 224
    5   UIKit                               0x000000010aaee52b -[UINib instantiateWithOwner:options:] + 1506
    6   UIKit                               0x000000010a946718 -[UIViewController _loadViewFromNibNamed:bundle:] + 242
    7   UIKit                               0x000000010a946d08 -[UIViewController loadView] + 109
    8   UIKit                               0x000000010a946f79 -[UIViewController loadViewIfRequired] + 75
    9   UIKit                               0x000000010a94740e -[UIViewController view] + 27
    10  UIKit                               0x000000010a8622c9 -[UIWindow addRootViewControllerViewIfPossible] + 58
    11  UIKit                               0x000000010a86268f -[UIWindow _setHidden:forced:] + 247
    12  UIKit                               0x000000010a86ee21 -[UIWindow makeKeyAndVisible] + 42
    13  UIKit                               0x000000010a812457 -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 2732
    14  UIKit                               0x000000010a8151de -[UIApplication _runWithMainScene:transitionContext:completion:] + 1349
    15  UIKit                               0x000000010a8140d5 -[UIApplication workspaceDidEndTransaction:] + 179
    16  FrontBoardServices                  0x000000010d5f25e5 __31-[FBSSerialQueue performAsync:]_block_invoke_2 + 21
    17  CoreFoundation                      0x0000000109eab41c __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    18  CoreFoundation                      0x0000000109ea1165 __CFRunLoopDoBlocks + 341
    19  CoreFoundation                      0x0000000109ea0947 __CFRunLoopRun + 887
    20  CoreFoundation                      0x0000000109ea0366 CFRunLoopRunSpecific + 470
    21  UIKit                               0x000000010a813b42 -[UIApplication _run] + 413
    22  UIKit                               0x000000010a816900 UIApplicationMain + 1282
    23  Calculator                          0x0000000109d6dcd7 main + 135
    24  libdyld.dylib                       0x000000010c23a145 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

Answer 1

您正在尝试将String值与Float值相乘/相加。此外，如果您将文字数字保留为无类型，则它们将为Double s，在没有强制转换的情况下也不会与Float混合。以下是有用的例子：

@IBAction func Calculate(sender: UIButton) {
    var a:Float = 66.0
    var b:Float = 13.7
    var c = (weightfield.text as NSString).floatValue
    var d:Float = 5.0
    var e = (heightfield.text as NSString).floatValue
    var f:Float = 6.8
    var g = (agefield.text as NSString).floatValue
    var result = a + (b * c) + (d * e) - (f * g)
    BMR.text = "\(result)"
}

将var转换为float以进行数学运算

1 个答案: