//init a NSArray
NSMutableArray*arr2= [NSMutableArrayarray];
for(inti=0; i<10; ++i) {
NSMutableDictionary*d = [NSMutableDictionarydictionaryWithObjectsAndKeys:[NSStringstringWithFormat:@"%d",i],@"a",nilnil];
[arr2addObject:d];
}
//Wrong
for(NSMutableDictionary*s in arr2) {
if([s[@"a"]isEqualToString:@"3"]) {
[arr2removeObject:s];//while here is safe for s[@"a"] = @"eeee";
}
}
//Safe 1.
[arr2enumerateObjectsUsingBlock:^(NSMutableDictionary*obj, NSUInteger idx,BOOLBOOL*stop) {
if([obj[@"a"]isEqualToString:@"3"]) {
*stop =YES;
[arr2removeObject:obj];// or obj[@"a"] = @"4ewewewe";
}
}];
//Safe 2.
NSArray*tmp = [NSArrayarrayWithArray:arr2];
for(NSMutableDictionary*s in tmp) {
if([s[@"a"]isEqualToString:@"3"]) {
s[@"a"] =@"eeee";
[arr2removeObject:s];
}
}
PS: 搜一句补充的话
//forin 循环中的便利内容不能被改变, 是因为如果改变其便利的内容会少一个, 而系统是不会允许这个发生的所以就会crash...但是当改变最后一个的内容时, 就不会crash, 是因为此时遍历已经结束, 结束之后对内容做修改是允许的。
