如题，用代码实现布局，ios6下报错，ios7不会报错 ，ios7下可用，但是ios6却会报错。怎么破？？ NSDictionary *views = NSDictionaryOfVariableBindings(newsScrollView,newsPageControl); [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0.0-[newsScrollView]-0.0-|" options:0 metrics:nil views:views]]; [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-64-[newsScrollView(==175.0)]" options:0 metrics:nil views:views]]; [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-261.0-[newsPageControl]-15.0-|" options:0 metrics:nil views:views]]; [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-208.0-[newsPageControl]" options:0 metrics:nil views:views]];