如何创建自己的方法,将块作为参数并稍后调用?
我试过以下事情。
#import <UIKit/UIKit.h>
typedef void (^viewCreator)(void);
@interface blocks2ViewController : UIViewController
{
}
-(void)createButtonUsingBlocks:(viewCreator *)block;
@end
- (void)viewDidLoad {
[super viewDidLoad];
[self createButtonUsingBlocks:^(NSString * name) {
UIButton *dummyButton = [[UIButton alloc]initWithFrame:CGRectMake(50, 50, 200, 100)];
dummyButton.backgroundColor = [UIColor greenColor];
[self.view addSubview:dummyButton];
}];
}
-(void)createButtonUsingBlocks:(viewCreator *)block
{
// Do something
NSLog(@"inside creator");
}
我也尝试将块变量传递给我的自定义方法但没有任何成功。为什么会这样呢?这样做的正确方法是什么?
更新
这是文件is.h
:
#import <UIKit/UIKit.h>
typedef void (^viewCreator)(void);
@interface blocks2ViewController : UIViewController
{
}
- (void)createButtonUsingBlocks:(viewCreator)block;
@end
这是.m
文件:
#import "blocks2ViewController.h"
@implementation blocks2ViewController
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
[super viewDidLoad];
[self createButtonUsingBlocks:^(NSString * name) {
UIButton *dummyButton = [[UIButton alloc]initWithFrame:CGRectMake(50, 50, 200, 100)];
dummyButton.backgroundColor = [UIColor greenColor];
[self.view addSubview:dummyButton];
[dummyButton release];
}];
}
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload {
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
// ...
-(void)createButtonUsingBlocks:(viewCreator)block
{
// viewCreator;
NSLog(@"inside creator");
}
@end
答案 0 :(得分:13)
首先如果你想让你的块采用字符串参数,那么typedef
是关闭的:
typedef void (^viewCreator)(NSString*);
其次块的类型是:
ReturnType (^)(ParameterTypes...)
而不是
ReturnType (^*)(ParameterTypes...)
因此无需添加指向viewCreator
类型的指针:
- (void)createButtonUsingBlocks:(viewCreator)block;
第三次如果你还没有这样做,你实际上必须调用该块:
-(void)createButtonUsingBlocks:(viewCreator *)block {
block(@"button name");
// ...
第四,最后,UIButton
被过度保留 - 您应release
或autorelease
:
UIButton *dummyButton = [[UIButton alloc] initWithFrame:...];
// ...
[self.view addSubview:dummyButton];
[dummyButton release];
投掷所有这些:
#import <UIKit/UIKit.h>
typedef void (^viewCreator)(NSString*);
@interface blocks2ViewController : UIViewController {}
-(void)createButtonUsingBlocks:(viewCreator)block;
@end
@implementation blocks2ViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self createButtonUsingBlocks:^(NSString *name) {
UIButton *dummyButton =
[[UIButton alloc] initWithFrame:CGRectMake(50, 50, 200, 100)];
dummyButton.backgroundColor = [UIColor greenColor];
[self.view addSubview:dummyButton];
[dummyButton release];
}];
}
-(void)createButtonUsingBlocks:(viewCreator)block {
block(@"my button name");
}
@end
答案 1 :(得分:6)
您也可以这样做而无需预先定义方法:
@interface blocks2ViewController : UIViewController
-(void)createButtonUsingBlocks:(void (^)(NSString *name))block;
@end
- (void)viewDidLoad {
[super viewDidLoad];
[self createButtonUsingBlocks:^(NSString * name) {
UIButton *dummyButton = [[UIButton alloc]initWithFrame:CGRectMake(50, 50, 200, 100)];
dummyButton.backgroundColor = [UIColor greenColor];
[self.view addSubview:dummyButton];
}];
}
-(void)createButtonUsingBlocks:(void (^)(NSString *name))block
{
block(@"My Name Here");
}