Block 定义
returnType (^ BlockName)(arguments, arguments,……);
Forexample: void (^ completeBlock)(int value, NSString *string);
Block 的使用
有返回值的 Block 使用
//申明
typedef int (^firstCompleteBlock) (int argumentOne, int argumentTwo);
//下面的类型，不推荐
//申明类型，省略形参：typedef int (^firstCompleteBlock) (int , int );
//定义为属性
@property(nonatomic, copy)firstCompleteBlock fcblock;
block 的实现：firstCompleteBlock fcblock;
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Blcok 作为属性,有返回值有参数
typedef int (^firstCompleteBlock) (int argumentOne, int argumentTwo);
@property(nonatomic, copy)firstCompleteBlock fcblock;
self.fcblock = ^int(int argumentOne, int argumentTwo) {
return argumentOne * argumentTwo;
};
int resulst = self.fcblock(10, 5);
NSLog(@"值为：%d", resulst);
输出：2019-05-16 16:41:31.280026+0800 Test[1282:68696] 值为：50
Block 作为方法参数,有返回值有参数
typedef int (^firstCompleteBlock) (int argumentOne, int argumentTwo);
@property(nonatomic, copy)firstCompleteBlock fcblock;
//方法实现
- (int) setOtherValue:(NSString *)value block:(firstCompleteBlock)compleBlock {
NSLog(@"block %@ 返回值", value);
int a = compleBlock(2, 8);
NSLog(@"completeBlock 值为：%d", a);
return a;
}
//调用方法
int b = [self setOtherValue:@"有" block:^int(int argumentOne, int argumentTwo) {
return argumentOne + argumentTwo;
}];
NSLog(@"block 回调有返回值： %d", b);
输出：
2019-05-16 16:41:31.280309+0800 Test[1282:68696] block 有 返回值
2019-05-16 16:41:31.280472+0800 Test[1282:68696] completeBlock 值为：10
2019-05-16 16:41:31.280642+0800 Test[1282:68696] block 回调有返回值： 10
Blcok 作为方法的返回值,有返回值有参数
typedef int (^firstCompleteBlock) (int argumentOne, int argumentTwo);
@property(nonatomic, copy)firstCompleteBlock fcblock;
//实现
- (firstCompleteBlock) setOtherValue:(NSString *)value successBlock:(firstCompleteBlock)completeBlock {
NSLog(@"block %@ 方法的返回值", value);
int b = completeBlock(8, 32);
NSLog(@"completeBlock 值实现后是：%d", b);
return ^(int one, int two){
int c= one * two;
NSLog(@"-------->> %d", c);
return c;
};
}
//调用, 这里对block的调用有没有想到响应式编程的感觉
int d = [self setOtherValue:@"是" successBlock:^int(int argumentOne, int argumentTwo) {
return argumentOne + argumentTwo;
}](4, 5);
NSLog(@"block 的值是：%d", d);
输出：
2019-05-17 12:14:25.221920+0800 Test[3712:60491] block 是 方法的返回值
2019-05-17 12:14:25.222350+0800 Test[3712:60491] completeBlock 值实现后是：40
2019-05-17 12:14:25.222582+0800 Test[3712:60491] -------->> 20
2019-05-17 12:14:25.222756+0800 Test[3712:60491] block 的值是：20
有返回值，无参数
typedef int (^BlockTest) (void);
@property(nonatomic, copy)BlockTest blockTest;
self.blockTest = ^int(){
NSLog(@"blockTest 计算值为：%@", @"🈶值");
return 10;
};
int c = self.blockTest();
NSLog(@"blockTest 无参数，有返回值是：%d", c);
输出：
2019-05-17 12:50:53.533606+0800 Test[4121:74646] blockTest 计算值为：🈶值
2019-05-17 12:50:56.547803+0800 Test[4121:74646] blockTest 无参数，有返回值是：10
无返回值的 Block
Block 无返回值，但有参数
typedef void (^BlockTest) (int argumentOne, int argumentTwo);
@property(nonatomic, copy)BlockTest blockTest;
self.blockTest = ^(int argumentOne, int argumentTwo) {
NSLog(@"blockTest 计算值为：%d", argumentOne + argumentTwo);
};
self.blockTest(20, 80);
输出：
2019-05-17 12:36:54.927784+0800 Test[3983:69324] blockTest 计算值为：100
无返回值，无参数
typedef void (^BlockTest) (void);
@property(nonatomic, copy)BlockTest blockTest;
self.blockTest = ^void(){
NSLog(@"blockTest 计算值为：%@", @"没🈶值");
};
//简化形式
//self.blockTest = ^{
// NSLog(@"blockTest 计算值为：%@", @"没🈶值");
// };
self.blockTest();
输出：
2019-05-17 12:39:42.019343+0800 Test[4025:70776] blockTest 计算值为：没🈶值
Block 简单实践
Block属性传值
@property(nonatomic, copy) void (^sencondCompleteBlcok)(NSString *value);
// block 属性内部传值
- (void) blockInObjcMethod {
__weak typeof(self) weakSelf = self;
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(4 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
__strong typeof(weakSelf) strongSelf = weakSelf;
strongSelf.sencondCompleteBlcok(@"属性 block");
});
}
//调用
[self blockInObjcMethod];
self.sencondCompleteBlcok = ^(NSString *value) {
NSLog(@"回调传的值是： %@", value);
};
输出：2019-05-16 15:44:21.499789+0800 Test[1088:50961] 回调传的值是： 属性 block
typedef 定义Block
block 作为方法参数
//申明定义block
typedef void (^firstCompleteBlock) (NSString *value);
//方法实现
+ (void) blockInClassMethod:(firstCompleteBlock)block{
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2* NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
NSLog(@"--->>> typedef block 打印");
block(@"typedef Block");
});
}
//方法调用
[ViewController blockInClassMethod:^(NSString *value) {
NSLog(@"类方法回调 %@", value);
}];
输出：
2019-05-16 15:44:19.101583+0800 Test[1088:50961] --->>> typedef block 打印
2019-05-16 15:44:19.101854+0800 Test[1088:50961] 类方法回调 typedef Block
作为属性
typedef void (^firstCompleteBlock) (NSString *value);
@property(nonatomic, copy)firstCompleteBlock fcblock;
//注意：先定义，才能使用，否则Crash
self.fcblock = ^(NSString *value) {
NSLog(@"%@ 打印", value);
};
self.fcblock(@"-------->> fcblock");
输出：
2019-05-16 16:02:14.104871+0800 Test[1128:56500] -------->> fcblock 打印
